In the food packaging industry, demand for convenience features is a growing trend, with consumers looking for packaging that can be easily handled and used. Reclosability in packaging not only offers consumer convenience, but also provides longer shelf life of the packaged product without the need to transfer contents into a separate reclose package, such as a food storage bag, Ziploc bag, for example.
Reclosable packaging structures are achieved by designing a multilayer structure in such a way that the interfacial strength between the sealant layer and an adjacent delamination layer with adhesive functionality is lower than the strength between the seal layer and the film structure. When the multilayer film is pulled from a container, the sealant layer ruptures and delaminates from the adjacent delamination layer. Sealant residue is deposited on the surface of the container and the surface of the delamination layer is exposed. When a pressure sensitive adhesive (PSA) layer is used as the delamination layer, resealability can be obtained by exposing the tacky surface of the PSA layer.
Conventional reclose systems are limited in availability and have shortcomings such as excessive fabrication steps and poor processability. Conventional reclose systems are typically coated water-based acrylics and require lamination, die-cutting, and other secondary processing steps. Hot melt adhesives based on styrenic block copolymers (SBC) eliminate some processing steps but are difficult to process and are not approved for direct food contact.
A need exists for an adhesive composition with reclosability that is safe for food contact (food-safe). A need further exists for a pressure sensitive adhesive (PSA) composition that is food-safe, reclosable, and extrudable for PSA film production.